You can be self-employed under an E-2 visa, and your wife can get work authorization if you have that (not necessarily helping you in your business, the authorization covers any job essentially).
E-2 is called the "treaty investor" category, you specifically need a non-immigrant visa for it, unless you're from BC you apply to the US consulate in Toronto for it.
http://toronto.usconsulate.gov/content/ ... ment=evisa
E visas are very complex to get, and I wouldn't attempt it on your own unless you've got signficant experience running your own business and have a good understanding of preparing financial statements, business plans etc. USCIS usually direct you to the SBA if you need help, however there are immigration consultants who specialize in helping with E visas and it's one of the situations where it will help you a lot if you can find a good one.
E-2 is valid for two years but can be renewed indefinitely. The big snag with it is if you have children, because although they can go to school, they cannot remain in the US when they reach the age of 21 (unless they get some other sort of status) and they cannot get work authorization either.
Plus if you send them to university, they have to use F-1 which means you have to pay foreign tuition rates.
Steve.